Fig. 3. Nocturnal and diurnal energy expenditure in relation to chaff/seed ratio and ambient temperature. Nocturnal energy expenditure (kJ 14 h^-1) was negatively related to temperature (F_1,84=1393, P<0.001) and chaff/seed ratio (F_1,84=22.0, P<0.001), and positively to their interaction (F_1,84=5.74, P=0.019) and body mass (F_1,93=11.8, P<0.001). Diurnal energy expenditure (kJ 10 h^-1) was negatively related to chaff/seed ratio (F_1,85=15.5, P<0.001) and temperature (F_1,85=2265, P<0.001) and positively to body mass (F_1,93=5.83, P=0.018), and there was no interaction between temperature and chaff/seed ratio (F_1,84=0.13, P=0.72). The plotted data are not corrected for body mass. Values are means ± S.E.M. (N=12).